Process for modifying gluco-oligosaccharides

Abstract

The present invention relates to an enzymatic process for elongating gluco-oligosaccharides with a glucosyl moiety. The invention also relates to the elongated gluco-oligosaccharides obtained with the process. These elongated gluco-oligosaccharides can be used in edible products, for instance as sweeteners and/or (low calorie) bulking agents and present a decreased digestibility compared to known gluco-oligosaccharides.

1 . A process for elongating gluco-oligosaccharides with at least one α-(1,2)-terminally linked glucosyl moiety, comprising the steps of:
 providing an acceptor composition comprising gluco-oligosaccharides having a degree of polymerization of 2, 3, 4, 5 or 6 glucosyl moieties, wherein each gluco-oligosaccharide comprises at least one α-(1,4)-linkage and wherein the acceptor composition comprises at least two gluco-oligosaccharides having a different degree of polymerization; 
 placing the acceptor composition in fluid contact with a polypeptide having kojibiose phosphorylase activity in the presence of a 1-glucosyl phosphate donor. 
 
     
     
         2 . The process according to  claim 1 , wherein the acceptor composition comprises at least 3, preferably at least 4 gluco-oligosaccharides having a different degree of polymerization. 
     
     
         3 . The process according to  claim 1 , wherein the acceptor composition is a partially hydrolyzed starch having a dextrose equivalent (DE) of less than 60. 
     
     
         4 . The process according to  claim 3 , wherein the partially hydrolyzed starch is a maltodextrin or glucose syrup. 
     
     
         5 . The process according to  claim 1 , wherein the acceptor composition comprises at least two different gluco-oligosaccharides selected from the group consisting of maltose, maltotriose, maltotetraose, maltopentaose and maltohexaose. 
     
     
         6 . The process according to  claim 1 , wherein the 1-glucosyl phosphate donor is β- D -glucose-1-phosphate. 
     
     
         7 . The process according to  claim 1 , wherein the polypeptide having kojibiose phosphorylase activity is a recombinant kojibiose phosphorylase. 
     
     
         8 . The process according to  claim 1 , wherein the process further comprises a step of preparing the 1-glucosyl phosphate donor by placing maltose in fluid contact with a polypeptide comprising maltose phosphorylase activity, and phosphoric acid and/or a salt thereof. 
     
     
         9 . The process according to  claim 8 , wherein the polypeptide comprising maltose phosphorylase activity is a recombinant maltose phosphorylase. 
     
     
         10 . The process according to  claim 1 , wherein the process further comprises a step of preparing the 1-glucosyl phosphate donor by placing trehalose in fluid contact with a polypeptide comprising trehalose phosphorylase activity, and phosphoric acid and/or a salt thereof. 
     
     
         11 . A composition comprising elongated gluco-oligosaccharides obtainable by the process according to  claim 1 . 
     
     
         12 . A composition comprising gluco-oligosaccharides elongated with at least one α-(1,2)-terminally linked glucosyl moiety, wherein the gluco-oligosaccharides have a degree of polymerization of 2, 3, 4, 5 or 6; and wherein the composition comprises at least two gluco-oligosaccharides having a different degree of polymerization and wherein each gluco-oligosaccharide comprises at least one α-(1,4)-linkage. 
     
     
         13 . The composition according to  claim 11 , wherein the elongated gluco-oligosaccharides comprise saccharide linkages selected from α-(1,2)-; α-(1,4)- and other saccharide linkages; wherein the amount of α-(1,4)-linkages is more than 50% and the amount of α-(1,2)-linkages is less than 50% of all saccharide linkages, excluding the linkages from kojibiose and kojioligosaccharides. 
     
     
         14 . The composition according to  claim 11 , further containing one or more of kojibiose, kojitriose, kojitetraose and kojipentaose. 
     
     
         15 . The composition according to  claim 11 , comprising at least 20 wt. % of elongated gluco-oligosaccharides based on the total weight of the product as dry substance. 
     
     
         16 . The composition according to  claim 11 , comprising at least two different elongated gluco-oligosaccharides selected from: 
       
         
           
           
               
               
           
         
         (α-D-Glucopyranosyl-(1→2)-α-D-glucopyranosyl-(1→4)-D-glucopyranose) 
       
       
         
           
           
               
               
           
         
         
           2-O-α-D-glucosyl-maltotriose 
         
         (α-D-Glucopyranosyl-(1→2)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-D-glucopyranose) 
       
       
         
           
           
               
               
           
         
         
           2-O-α-D-glucosyl-maltotetraose 
         
         (α-D-Glucopyranosyl-(1→2)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-D-glucopyranose) 
       
       
         
           
           
               
               
           
         
         
           2-O-α-D-glucosyl-maltopentaose 
         
         (α-D-Glucopyranosyl-(1→2)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-D-glucopyranose) 
       
       
         
           
           
               
               
           
         
         
           2-O-α-D-glucosyl-maltohexaose 
         
         (α-D-Glucopyranosyl-(1→2)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-α-D-glucopyranosyl-(1→4)-D-glucopyranose) 
       
     
     
         17 . A foodstuff, pet food, feed or personal care product comprising the composition according to  claim 11 . 
     
     
         18 . The process according to  claim 1 , wherein the acceptor composition is a partially hydrolyzed starch having a dextrose equivalent (DE) of less than 50. 
     
     
         19 . The process according to  claim 1 , wherein the polypeptide having kojibiose phosphorylase activity is a recombinant kojibiose phosphorylase obtainable from a bacterium selected from the group consisting of  Thermococcus barophilus, Pseudothermotoga thermarum, Thermoanaerobacter brockii, Thermoanaerobacterium thermosacharolyticum, Caldicellulosiruptor saccharolyticus, Pyrococcus  sp.,  Palaeococcus pacificus  and  Thermofilum pendens.    
     
     
         20 . The process according to  claim 8 , wherein the polypeptide comprising maltose phosphorylase activity is a recombinant maltose phosphorylase obtainable from a bacterium selected from the group consisting of  Lactobacillus acidophilus, Bacillus selenitireducens, Enterococcus faecalis, Lactobacillus brevis, Lactobacillus sanfranciscensis, Paenibacillus  sp. and  Bacillus  sp.